1. Field of the Invention
The present invention relates to a stopping apparatus which abuts against a work being conveyed to stop the work.
2. Description of the Related Art
There is known a stopping apparatus for stopping, at a predetermined position, a work being conveyed on a conveying apparatus such as a roller conveyor (Japanese Patent Laid-Open Nos. 6-16233, 8-319023 and 11-227937). The stopping apparatus stops a work or cancels the stop of the work by moving an abutment portion such as a roller which abuts against the work onto a conveying apparatus or retreating it from the conveying apparatus. For this reason, a mechanism and actuator for moving the abutment portion are required.
As the mechanism for moving the abutment portion onto the conveying apparatus or retreating it from the conveying apparatus, a structure by which the abutment portion is reciprocally moved along a straight line and a structure by which the abutment portion is reciprocally moved by pivotal motion (this will be referred to as a pivot type hereinafter) are proposed. The pivot type can retreat the abutment portion with a smaller force than that of the structure by which the abutment portion is reciprocally moved along the straight line.
In the pivot type, a pivot shaft is often located on the upstream or downstream side of the abutment portion in a convey direction below a convey surface. In the structure in which the pivot shaft is located on the upstream side of the abutment portion, the pivot shaft is located in a region below the work which abuts against the abutment portion and is stopped. However, the region below the work is often used as a space in which an apparatus for lifting the stopped work or various sensors for confirming the stop of the work are disposed. For this reason, it is often difficult to ensure a space in which the stopping apparatus is disposed.
In the structure in which the pivot shaft is located on the downstream side of the abutment portion, when retreating the abutment portion to cancel the stop, the abutment portion draws an arcuate moving locus along which the abutment portion slightly moves toward the upstream side. For this reason, the work is slightly pushed back to the upstream side. An extra actuator output is required by this push-back force.